The study, published in the American Journal of Clinical Nutrition, is the first long-term, pan-European clinical trial looking at the impact of a Mediterranean diet on bone health in older adults.

"This is a particularly sensitive area for osteoporosis as loss of bone in the femoral neck is often the cause of hip fracture, which is common in elderly people with osteoporosis," said Susan Fairweather-Tait , a professor at the University of East Anglia in the UK.

More than 1,000 people aged between 65 and 79 took part in the trial, and volunteers were randomised into two groups - one which followed a Mediterranean diet and a control group which did not.

Bone density was measured at the start and after 12 months. The diet had no discernible impact on participants with normal bone density, but it did have an effect on those with osteoporosis.

People in the control group continued to see the usual age-related decrease in bone density, but those following the diet saw an equivalent increase in bone density in one part of the body - the femoral neck.

This is the area which connects the shaft of the thigh bone to its rounded head, which fits in the hip joint.

"Bone takes a long time to form, so the 12-month trial, although one of the longest to date, was still a relatively short time frame to show an impact. So the fact we were able to see a marked difference between the groups even in just this one area is significant," Fairweather-Tait said.